Update: See the comments to see how to do this correctly.

the UNIX grep command is very powerful, but the egrep command is even more powerful. You can grep for multiple strings in a file using the egrep command. All you have to do is use the | (or) symbol and add as many strings you want to look for. You have to make sure you escape the pipe symbol. This is especially helpful when you are wading through log files.

egrep "string 1"\|"string 2" file.log

The above command will only display the lines from file.log that have a reference of “string 1” and “string 2”